Australian research findings may change how oxygen is used in ICUs worldwide

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A world-first trial by researchers at Monash University could change how oxygen is administered to millions of people in intensive care units across the world. The trial found ICU patients are being given unnecessary levels of oxygen that make no difference to their recovery, and in some specific groups less oxygen may actually improve recovery and survival rates.

The findings of the study, “Conservative Oxygen Therapy during Mechanical Ventilation in the ICU”, are published in the New England Journal of Medicine and were presented at the World Conference of Intensive Care in Melbourne on October 15th.

One of the lead researchers, Professor Rinaldo Bellomo from Monash University’s Australian & New Zealand Intensive Care (ANZIC) Research Centre, said the findings are hugely significant for the use of oxygen in ICUs around the world.

“Everyone in intensive care gets oxygen – approximately four million patients a year in resource rich countries - so it’s a massive issue. But there’s been an underlying assumption that oxygen is good for patients and doctors should give it to them liberally and should make sure the oxygen levels are high,” Professor Bellomo said.

“But there’s never been any data or evidence or trial that that’s actually true.” In the study, 1,000 patients in Australian and New Zealand ICUs were assigned to two groups – one receiving the normal amount of oxygen, and the other a smaller, or “conservative”, amount of oxygen.

The results found that there was no difference in outcomes between the groups, meaning there is no longer any reason to provide the high amount of oxygen typically given to ICU patients on breathing machines, Professor Bellomo said.

“We think that this will bring about, across the board and the world, a decrease in the amount of oxygen therapy that’s being given because it’s likely to be seen to be unnecessary,” Professor Bellomo said.

However, during the study the researchers found some results that could suggest too much oxygen could actually be harmful in people who have suffered hypoxic brain injury due to cardiac arrest.

“These results showed that in those patients treated with conservative oxygen therapy, there is a signal to suggest increased survival with less oxygen. So even though the totality of ICU patients put together do not appear to show a difference between these two treatments, in some specific sub-groups of people, giving less oxygen may well be a good thing,” Professor Bellomo said.

The research team is now planning further investigation into this sub-group with bigger and more targeted trials.

“Until now, in ICU, oxygen has been treated a bit like holy water. But increasingly it’s being shown to be like lots of other things that were done because they seemed like a good idea at the time but now need to be rigorously tested for safety and efficacy. When you put liberal oxygen therapy under the crucible of a large, multi-centre randomised control trial, it doesn’t really seem to offer appreciable advantages and may be dangerous for some patients. More large trials of oxygen therapy are now a global priority,” Professor Bellomo said.

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